fix: file transfer system critical bugs and add persistence

- Fix recovery logic: save transfer data before cleanup so recovery
  can actually use it to restart transfers
- Register GMCPClientFile package so Client.File.Download messages
  are handled (was silently dropped)
- Fix error handling in handleIncomingChunk: capture hash from header
  so errors report actual hash instead of "unknown"
- Add error handling to acceptTransfer in client.ts
- Wire up FileTransferStore for IndexedDB persistence:
  - Chunks saved as they arrive for resumable transfers
  - Metadata tracked for incomplete transfers
  - Cleanup on completion, hash mismatch, or cancellation

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Author: ctoth

src/App.tsx

@@ -25,6 +25,7 @@ import {
   GMCPCharStatusAffectedBy, // Added
   GMCPCharStatusConditions, // Added
   GMCPCharStatusTimers,
+  GMCPClientFile,
   GMCPClientFileTransfer,
   GMCPClientHtml,
   GMCPClientKeystrokes,
@@ -96,6 +97,7 @@ function App() {
     newClient.registerGMCPPackage(GMCPCommLiveKit);
     newClient.registerGMCPPackage(GMCPAutoLogin);
     newClient.registerGMCPPackage(GMCPClientHtml);
+    newClient.registerGMCPPackage(GMCPClientFile);
     newClient.registerGMCPPackage(GMCPClientFileTransfer);
     newClient.registerGMCPPackage(GMCPCharItems);
     newClient.registerGMCPPackage(GMCPCharStatus); // Removed duplicate below